Determination of cephalexin in oral suspensions by micellar electrokinetic chromatography.

A simple and efficient micellar capillary electrophoresis method for the analysis of cephalexin in oral suspensions is described. The analysis was carried out in a bare silica capillary with 75 microm i.d. and total length of 50 cm (28 cm to the detector) with a buffer solution containing 20 mM sodium tetraborate, 20 mM sodium dodecyl sulfate, and 0.1% laurylpolyoxiethylenic ether. The applied voltage was 15 kV. Detection was achieved by ultraviolet absorption at 210 nm. The calibration curve was linear within the concentration range from 40.0 to 120 microg/mL with a correlation coefficient of 0.9998. The percentage recovery was found to be 100.09 +/- 0.56. The method showed good selectivity and resolution of the drug impurities, and was found suitable to study cephalexin stability in pharmaceutical preparations.